It is well known that windows and windshields, such as those incorporated in motorcycle helmets, can be defogged by applying heat. In general, two approaches have been utilized to heat windows and helmet shields. One approach is to mount a pair of spaced-apart bus bars connected together by a plurality of thin wires on a transparent substrate. An alternative approach is to replace the thin wires with a layer of indium tin oxide (ITO). Depending upon the application, the transparent substrate is adhesively attached to, or mechanically mounted on, the window or helmet shield to be defrosted. Examples of such systems applied to helmet shields are described in U.S. Pat. Nos. 3,024,341; 4,584,721 and 4,682,007. For various reasons, the use of ITO to defog helmet shields has not been entirely satisfactory.
Ski and other goggles, like windows and helmet shields, frequently have fogging problems. Originally, ski goggle lenses, as many other goggles, were formed of a single layer of transparent plastic material mounted in a frame. In order to reduce fogging, air passageways were created in the frames of ski goggles. Unfortunately, snow, particularly wet snow, quickly reduces the effectiveness of such air holes. Another way of reducing the fogging of ski goggles that has been used in the past is to make the lens of multiple transparent layers separated by a dead air space. While the foregoing and other approaches have reduced ski goggle fogging, they have not entirely eliminated this problem. Depending upon their use, other goggles also can have fogging problems.
The present invention is directed to providing ski and other goggles that incorporate a heating system for defogging the lens of the goggles.